profile control (love) 012613 - 5counties.org · rock ramps/chutes & pools/cascades 44 in...

Profile Control

Michael Love, P.E.

[email protected]

Tools for Aquatic Organism Passage

Replacement/RemovalRetrofit New

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Stream CrossingProject

Profile Control

Increasing Ecological Function

Geomorphic ApproachesHydraulic Approaches

3

Profile Control Options

Slope Pros / Cons

Restored Profile

Limited by channel type

+ Passage diversity, Habitat

- Scale/cost

Roughened Channel

Durability, bedload limit

+ Passage diversity

- Species, failure risk

Boulder Weirs<5%

+ Passage diversity, Habitat

- Failure risk

Rigid Weirs(log, concrete) <5%

+ Rigid, durable

- Species, habitat

Technical Fishway 10% or

“vertical”

+ Small footprint

- Species specific, flow, sediment, debris

Design Profiles for Incised Channels: Replacement

Design Profile: Stream Simulation with Uncontrolled Regarde (headcutting)

Design Profile: Forced Profile(rock weirs, roughened channel…)

Design Profile: Combined Forced Profile & Stream Simulation

Design Profiles for Incised Channels- Retrofit or Replacement -

Design Profile:Downstream Forced Profile

Design Profile:Restored Channel Profile

6

Channel restoration for passage of aquatic organisms

Planform restoration

Profile restoration

Restored channel

Profile Restoration

From Christine Chann, San Pedro Creek Watershed Coalition

Restored 1,300 feet of incised channel:• Stabilized Banks • Created Instream and Riparian Habitat • Eliminated a Culvert Barrier

From Christine Chann, San Pedro Creek Watershed Coalition

Profile Restoration

From Christine Chann

• Sloped-back banks to reduced entrenchment

• Raised channel bed as much as 8 feet using native and imported fill

• Increase bankfull width by 20% and built floodplains

• Installed profile control to force riffles and pool

From Syd TempleProfile Restoration

10

Channel restoration for fish passage correction

Constructed 2000Photos from 2005

Profile RestorationOutlet Creek

Photos from Kozmo Bates

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Upstream of CulvertNo Incision Experienced

Profile RestorationOutlet Creek

Downstream of Project Channel Remains Incised

Photos from Kozmo Bates

Site 10 was constructed as a spanner racked additional wood. Looking downstream and aggradation is along right bank.

Wood Count: 93 total wood fractions (Volume: 60.9 cubic meters)17 large trees with rootwads, 69 large logs, 3 medium logs, 4 bunches of “small wood debris” (aka slash)

From Joe’l Benegar & Rocco Fiori 12



Before

After

15

Geomorphically-Based Roughened Channels

Channel constructed steeper than the adjacent channel (profile control)

Based on morphology of steeper stream channel

Stable engineered streambed material (ESM)forms channel bed & banks

Quazi-hydraulic design for target species/lifestages(velocity, depth, drop, EDF)

Examples of a Roughened Channel in Europe

3% - 1%10%- 3%30%-10%

Source Transport Response

InitiationScour

Deposition

Large Woody DebrisLarge and immobile,

traps sedimentMobile, transports

with sediment

>20% 2% - 0.1% < 0.1%Slope:

(from Montgomery and Buffington, 1993)

Generalized Stream Classification

17

Natural Steep Stream MorphologySteep Boulder-Cobble Stream Channels

Plane-bed

Step-Pool

Cascades

Natural Step Pool Stream Morphology

Step Pool Stream Channels

Geomorphically-Based Roughened Channel ConceptCommon Channel Types

Roughened Riffles

Plane Bed Channel (rock ramps)

Rapids or Chutes & Pools

Step-Pools

Cascades & PoolIncr

easi

ng S

lope

Caution:

Only use channel types & slopes that the target species/lifestage are known to ascend

Risk increases further the roughened channel characteristics deviates from the natural channel(i.e. slope, bed material, entrenchment) 20

Plane-Bed (Rock Ramp) Roughened Channels

Grub Creek “Rock Ramp”

Slope & Length Thresholds:

Slope Range: < 4%

Max Head Diff.: 5 feet

Use chutes and Pools for Larger Head Differentials

Bed Morphology:

Random placement of rock

D100 < Channel Depth

21

Woodacre Creek at San Geronimo Valley Road

Before

2 Years After

Plane-Bed (Rock Ramp) Roughened ChannelsFish Passage Pros:

Doesn’t rely on leaping abilities

Large amount of hydraulic diversity at all flows

Cons:

Shallow depths at low flows

High flow passage often limited by turbulence

Rock RampCulvert Outlet Pool (Energy Dissipation)

Profile 23

Chutes & Pools Roughened ChannelsSlope & Length Thresholds (for armored pools):

Slope Range: < 8% across a chute< 4% overall

Max Head Diff.: 2 feet per chute

Bed Morphology:

Chutes (Rapids) with Random Rock Placement

D100 < Channel Depth

Pools Armored with Coarse Bed Material

Typical Chutes & Pools Roughened Channel

Plan

Profile25

Fish Passage Pros:

No leaping required

Large amount of hydraulic diversity

Pools provide resting/ holding habitat and dissipate energy

Chutes & Pools Roughened ChannelsCons:

Shallow depths at low flows, especially on steep chutes

High flow passage often limited by turbulence

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Concrete sills provide added stability & control subsurface flow

NID Measurement Weir

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NID Measurement Weir

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Step-Pool Roughened ChannelsSlope & Length Thresholds:

Slope Range: 3% to 6.5% overall

Bed Morphology:

Rhythmic Pattern of Boulder Steps/Weirs

Larger Rocks in Step 0.5 to 1.0 Bankfull Depth

Oversized Pool every 3 to 5 feet of drop

Pools Armored with Coarse Bed Material

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Step-Pool Roughened Channels

D50 of Rocks forming Step ≈ Step Height (H)(Chin 1999; Chartrand & Whiting, 2000)

Drop Height (h) & Pool Depth (dr) should satisfy fish passage criteria

Morphology of Steps (general guidance): Step-pool channel slopes <4%:

2 < H/L/S < 5 (Chin 1998)

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Fish Passage Pros:

Good low-flow passage


Step-Pool Roughened ChannelsCons:

May require fish to leap

Challenging to construct complex steps

Not suited for large, wide or unconfined streams

Steeper slopes with small drops (i.e. 6 inch) result in small pools

• Less holding/energy dissipation

• Channel instability (streaming flows)

Photo: Roger Leventhal

Step31

Gulch 7 Step Pool Roughened Channel-Stream Simulation Hybrid

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2006

Gulch 7 Step Pool Roughened Channel-Stream Simulation Hybrid

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2013

Cascade & Pool Roughened ChannelsSlope & Length Thresholds:

Slope Range: > 5% cascade> 4% overall

Bed Morphology:

Complex series of small drops and pools

Largest keystone boulders > bankfull depth

Drops and constructions form jet & wake hydraulics

Armored pool every 3 to 5 feet of drop to dissipate energy Cascade Slope: 6%-7%

Overall Slope (w/pool): 4%

Fish Passage Pros:

Passage of non-leaping fish

Diverse high-flow hydraulics for passage


Cascade & Pool Roughened ChannelsCons:

Poor low-flow passage

Requires straight & entrenched channel reach

Considered experimental for juvenile passage, May require monitoring

Profile Control TransitionsChutes & Pools Roughened Channel

Low and HighPotential Profiles

Anticipated Lengthof Self-Forming Scour Pool

Lowest Potential Profile Elevation at End of Anticipated Scour Pool

ChutePoolChute

End of Chute

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Engineered Bed Material is:

• Larger than bedload transported into roughened channel

• No replacement by natural bedload material

• Sized to be stable to a bed design flow (Q100yr)

The Roughened Channel Design Concept

Limitation - Lack of Sediment Continuity

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The Iterative Design Process1. Calculate Qbed & Qfish

2. Develop initial channel shape & slope to fit site

3. Calculate Stable D84 rock size at Qbed:

Initial guess for D84Use hydraulic roughness relationships dependent on flow & substrate sizeCalculate Unit Discharge for channelCalculate a stable D84

5. Evaluate fish passage conditions

If unsuitable, change channel shape/slope and repeat no. 2-5

Developing the Channel Design and Bed Mixture

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Estimating Hydraulic Roughness

n = . 0.0926R1/6 .1.16+2log(R/D84)

(Limerinos, 1970)

(Bathurst, 1985)4Dhlog62.5

f8

8410

Flow resistance for steep mountain streams:

Numerous relationships developed with varying limitations.

See Appendix B in CDFG Part XII for more relationships.

84% of bed material finer than D84

Hydraulic Radius

Water Depth

Darcy Friction Factor

Manning’s roughness

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Designing a Stable Bed Using Unit Discharge Method

from ACOE EM 1110-2-1601 based on Abt et al, 1988

Unit discharge (cfs/ft) at stable bed design flow (100 year flow)

3

1

3

2555.0

30

25.195.1

g

qSD ACOE

Water surface slope

Gravitational acceleration (ft/s2)

Unit Discharge:

b

Qq

channel

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Developing Gradation of Bed Material

ACOE (1994) produces porous uniform gradation for bed material:

D84/D15 = 1.7 to 2.7

Natural channel streambed material has wide gradation:D84/D15 = 8 to 14 (typical in steeper streams)

• Larger Material (>D50) is framework for stability

• Smaller material (<D50) fills voids to control porosity

Porous Riffle-Pool Rock Chute

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Developing Engineered Streambed Material (ESM)

50n1

i Di2D

For Di < D50ESM useFuller-Thompson Equation:

n ranged from 0.45 to 0.70Set n to achieve D8 ~ 2mm

D84ESM = 1.5 (D30ACOE)(from WDFW, 2003)

Gradation Shift for ESM:Bed Gradation for Roughened Channel

0102030405060708090

100

0.01 0.1 1 10Relative Grain Size (Di/D84)

Pe

rce

nt

Fin

er D84

D100

D50

D16D8

For Di > D50ESM use Ratios Relative to D84:

D100ESM = 2.5(D84ESM)D50ESM = 0.4(D84ESM)(from WDFW, 2003)

Sometimes produces oversized rock 42

Sizing and Specifying Material Gradations

Percent of Mix

Range of Size(Intermediate Axis)

16 20 in 48 in

34 8 in 20 in

18 3 in 8.0 in

12 ¼ in 1.0 in

8 Passes Sieve #10 (2 mm)

Particle Distribution D95 = 4.1 ft

D84 = 1.7 ft

D50 = 7.9 in

D20 = 0.9 inD8 = 2 mm

0

20

40

60

80

100

0.0 0.0 0.1 1.0 10.0Size, ft

Pe

rce

nti

le

Example Specifications for Gradation of ESM

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Use largest size class to form structures (steps, keystones)

Pool

Evaluating Fish Passage ConditionsRock Ramps/Chutes & Pools/Cascades

44

In Ramps, Chutes & Cascades

• Ave. Cross Section Water Velocity (U)

• Max Water Depth

• Turbulence (EDF = gUS)

In Armored Pools

• Pool Depth

• Turbulence (EDF) from change in Velocity Head

gV

QhEDF

2

g

UUh poolchute

2

22

where,

85 90 95 100 105 110 115 120 125498

499

500

501

502

503

504

505

Stuart Creek Ex. and Proposed 30% Design Plan: Proposed 30% 5/9/2011

Station (ft)

Ele

vatio

n (

ft)

Legend

WS 5% EP

Crit 5% EP

0.0 ft/s

0.5 ft/s

1.0 ft/s

1.5 ft/s

2.0 ft/s

2.5 ft/s

3.0 ft/s

Ground

Levee

Ineff

Bank Sta

Roughened Chute Cross Section

Dividing Channel into SubsectionsRock Ramps/Chutes/Cascades

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Passage Conditions in SubsectionMean Width = 4.5 ft (DFG min = 4 ft)Ave. Depth = 0.76 ftAve. Velocity =1.45 ft/s

Flow in Section = 5.0 cfsWater Surface Slope = 0.03 ft/ftEDF = 2.7 ft-lb/s/ft3

Passage Corridor for Adult Resident Rainbow Trout

High Passage FlowAdult Resident Rainbow Trout

1. Grading and Compact

2. Placing Rock Structures

Construction Sequencing and Methods

46


3. Keystones and Bankline Rock

Photo by Mitch Farro

47


4. Stockpile Engineered Streambed Material onsite. Within a small section of channel, place material in correct proportions and mix with excavator bucket ... 48


4. ...If delivered premixed to site, must be remixed in channel due to settling in truck.

Delivered Premixed

5. Install Engineered Streambed Material (ESM)…

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5. ..Construct channel bed in lifts. Compact each lift.

50


6. Fill voids in bed and banks with finer material (typically river run).

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7. Flood channel bed and banklines to fill voids, compact bed, and wash fines off surface. Collect and remove fines from bottom of reach.

For best results: Flood each lift and then use a plate compactor

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Profile Control



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Forced Profiles with Drop StructuresDrop Structures

(weirs, sills, chutes):

• Discrete structures

• Distinct drops in the channel

• Native streambed material between

• Types: Flexible vs Rigid

55

Profile Control Transitions (Steps or Drop Structures)

Anticipated Lengthof Self-Forming Scour Pool

Anticipated Drop Across Weir (with scour pool)

Low and HighPotential Profiles

4 Profile ControlStructures toBackwater Culvert

< Drop Criteria for Target Fish Species/Lifestage

Place End of Profile Control based on Low Potential Profile with Anticipated Scour Pool

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Rock Weirs & Chutes• Irregular surface provide

hydraulic diversity

• Withstands small shifts, and easy to field adjust

• Maintains channel shape

• Lower cost than roughened channel

• Requires skilled operator

• Larger Vertical Tolerance

• Built at lower slopes than rigid weirs (max 4 to 5%)

• Cascading failure possible

Arch Shaped Rock Weirs

Shape of Rock Weirs

From CA DFG Restoration Manual, Part XII (2009)

Key into banks to

avoid flanking

Footing of Rock Weirs

> Calculated D100

60

Spacing of Rock Weirs

Drop

RockWeir

Pool scoured into native streambed material

~

Design Profile

DropOversteepened

Design Profile

~Small Pools,poor sealing, unstable rock

61

Rock Sizing for Weirs

CK

wDSD riprap

9.250

Far West States (FWS) Lane Method riprap sizing method (NRCS, 1996)

From Design of Rock Weirs (NRCS, 2000)

w = channel top width at the design flow (feet)

D = maximum depth of flow in channel (feet)

S = channel slope (feet/feet)

C = coefficient for channel curvature (1 for straight channels)

K = side slope coefficient. 0.53 for 1.5H:1V, 0.87 for 3H:1V,

D100-Weir = 4(D50-Riprap)D50-Weir = 2 (D50-Riprap) Dmin-Weir = 0.75 (D50-Riprap)

Rock Weir Gradation

62

Individual Chutes:• Energy dissipation• Diversity• Slope from crest to

crest typically < 3%

Shape of Chute:• Top width• Head differential (typ. 2 ft max)• Plan vee• Cross section vee• Low flow channel

Rock Riffles and Chutes as Drop Structures

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Riffles and Chutes

Spring Prairie CrCobble riffle

From Luther Aadland

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Rock Riffles and Chutes

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Rigid Weirs: Concrete, sheet pile, …• Objectives:

– Steepen grade (self sealing)

– Rigid permanent bed control to maintain steep grade

• Max 5% grade in small streams

• Prefabricated; installation easy but demands care

• Deeper keys into bed and banks than rock weirs

• Shape to fit channel and control thalweg (v-shape)

• Can add hydraulic complexity along crest to improve passage

Prefabricated

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67

3 pre-cast panels for channels up to 12 ft

Vary arch orientation at channel bends

Modular Arch Drop Structure

Elevation View

Plan View

Boulders keyed loose against weir crest boulders to form “cascade”

Notch to maintain channel thalweg

Existing Channel cross-section

Approx 1:1

Embedded eyes and pin to tie panels together.

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Log ControlsUsed to raise incised channel

Passage optimized,Habitat not

Log controls

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Horizontal Double Log Sills

• Keeps log wetted to increases longevity

• Easy to construct

• Spreads out flow

– Forms wide pools, rather than long

– Anticipate bank erosion when keying

• Wide smooth surface/ low hydraulic complexity

– May not be good for juvenile passage

Log controls

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2003

Failed after 20 years because no bedload

recruitment.

Wildcat Cr Dam bypass channel

Constructed 1983

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Structure flanked

Log control remainsstructurally sound

Three keys to stability

1. Double log, spiked2. Ballast

(concrete or rock)3. Tiedown

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Anticipated Scour Depth ≈ 2.0 to 2.5 X Drop Height

Drop Height

Log controls: Rule of Thumb for Scour

Top Log forward of bottom for nappe to freefall into pool

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http://www.wa.gov/wdfw/hab/engineer/cm/culvert_manual_final.pdf

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Index CreekVee log weirs

Complex Log Steps

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Physt R. trib

“X-weirs”

Barnard

Complex Log Steps

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Dunn Creek

Natural Log Steps

Training logs along bank confine flow

7777

Complex Log Steps

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Complex Log Steps

No Rock Used

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Log controls• Straight

– Objective: Steepen grade, optimize select passage, minimize cost and length, secure elevation control

– 5% grade max as bed retention– Uniform channel– Secure designs available

• V- Shape– Objective: Steepen grade, deepen thalweg,

narrow channel, provide select passage– More diverse channel

• Can be made complex• Durable



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Profile Control



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profile control (love) 012613 - 5counties.org · rock ramps/chutes & pools/cascades 44 in...

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